s = input()
s1 = ''
for a in s:
    if (a == '(' or a == '[' or a == '<') or s1 =='':
        s1 += a
    elif s1 != '':
        if (a == ')' and s1[-1] == '(') or (a == '}' and s1[-1] == '{') or (a == ']' and s1[-1] == '[') or (a == '>' and s1[-1] == '<'):
            s1 = s1[:-1]
if s1 == '':
    print('верная')
else:
    print('неверная')